Background: Ovarian cancer is the deadliest gynecological cancer, accounting for 15,520 deaths annually. One critically important yet often overlooked component to the tumor initiation and progression process is the tumor stromal microenvironment. Primarily composed of fibroblasts and extracellular matrix proteins (ECM) as well as some endothelial cells and immune cells, the tumor microenvironment has been shown to promote tumor initiation of normal epithelial cells and facilitate progression of malignant cells, thereby, presenting a unique approach to diagnosing, understanding and treating cancer. Objective/Hypothesis: Our preliminary studies as well as previously published studies indicate that the tumor microenvironment enables and promotes tumor progression and chemoresistance, possibly through the expression of SFRP2. We propose to develop relevant in vitro models to dissect these interactions and to illustrate the specific mechanisms with which the microenvironment promotes ovarian cancer development and progression. Specific Aims: (1) To develop and validate a practical and relevant 3D model for in vitro studies involving the tumor microenvironment and cancer; (2) To validate the expression of secreted factor SFRP2 primary human cultures of CAFs; (3) To evaluate the effects of SFRP2 on elements of ovarian cancer progression, such as cancer growth, adhesion, migration, invasion and angiogenesis; (4) To determine the pathways involved in the ovarian cancer progression initiated by SFRP2. Study Design: We will develop a practical and relevant 3D model of ovarian cancer in a tumor microenvironment that closely resembles histological characteristics of ovarian cancer and test the effects interactions between cancer and the tumor microenvironment, specifically SFRP2 using gene expression methods, purified protein, and primary cells in conventional 2D and newly developed 3D models. We will further characterize the molecular mechanisms that allow for the cancer progression and investigate the crucial signaling processes necessary for the tumor microenvironment interactions. Cancer Relevance: The work described in this proposal focuses on identifying the contributions of the tumor microenvironment to the progression of ovarian cancer by dissecting the signaling and interactive differences between normal and cancer cells and their respective microenvironments. Isolating these interactions will allow for better understanding of ovarian cancer progression as well as provide new approaches that alone or combined with current methods, may provide more reliable diagnostic protocols and more efficacious treatment options, potentially eliminating ovarian cancer as the deadliest gynecological cancer.